Docs » Autodocs » dos.library » Seek
Seek -- Set the current position for reading and writing
oldPosition = Seek( file, position, mode )
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LONG Seek(BPTR, LONG, LONG)
Seek() sets the read/write cursor for the file 'file' to the
position 'position'. This position is used by both Read() and
Write() as a place to start reading or writing. The result is the
current absolute position in the file, or -1 if an error occurs, in
which case IoErr() can be used to find more information. 'mode' can
be OFFSET_BEGINNING, OFFSET_CURRENT or OFFSET_END. It is used to
specify the relative start position. For example, 20 from current
is a position 20 bytes forward from current, -20 is 20 bytes back
from current.
So that to find out where you are, seek zero from current. The end
of the file is a Seek() positioned by zero from end. You cannot
Seek() beyond the end of a file.
file - BCPL pointer to a file handle
position - integer
mode - integer
oldPosition - integer
The V36 and V37 ROM filesystem (and V36/V37 l:fastfilesystem)
returns the current position instead of -1 on an error. It sets
IoErr() to 0 on success, and an error code on an error. This bug
was fixed in the V39 filesystem.
Read(), Write(), SetFileSize()
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